2-(thioamino)-4,6-diamino-1,3,5-triazines are known premature vulcanization inhibitors, U.S. patent application Ser. No. 148,061, filed May 12, 1980, now U.S. Pat. No. 4,301,260 issued Nov. 17, 1981. These known inhibitors are not commercially feasible because of their low potency.